linux-kernel-markers-documentation-update-flags
Documents the flag usage.
Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]>
--- a/Documentation/marker.txt
+++ b/Documentation/marker.txt
@@ -78,6 +78,21 @@ which saves a data cache hit, but also requires cross CPU
code modification. In
order to support embedded systems which use read-only memory for their code,
the
optimization can be disabled through menu options.
+The MF_* flags can be used to control the type of marker. See the
+include/marker.h header for the list of flags. They can be specified as the
+first parameter of the _MARK() macro, such as the following example which is
+safe wrt lockdep.c (useful for marking lockdep.c functions).
+
+_MARK(_MF_DEFAULT | ~_MF_LOCKDEP, subsystem_eventb,
+ MARK_NOARGS);
+
+Another example is to specify that a specific marker must never call printk :
+_MARK(_MF_DEFAULT | ~_MF_PRINTK, subsystem_eventc,
+ "%d %s %p[struct task_struct]",
+ someint, somestring, current);
+
+Flag compatibility is checked before connecting the probe to the marker.
+
* Probe example
@@ -122,6 +137,13 @@ void probe_subsystem_event(const char *format, ...)
va_end(ap);
}
+#define SUBSYSTEM_EVENTB_FORMAT MARK_NOARGS
+void probe_subsystem_eventb(const char *format, ...)
+{
+ /* Increment counters, trace, ... but _never_ generate a call to
+ * lockdep.c ! */
+}
+
static int __init probe_init(void)
{
int result;
@@ -130,16 +152,24 @@ static int __init probe_init(void)
probe_subsystem_event);
if (!result)
goto cleanup;
+ result = _marker_set_probe(_MF_DEFAULT & ~_MF_LOCKDEP,
+ "subsystem_eventb",
+ SUBSYSTEM_EVENTB_FORMAT,
+ probe_subsystem_eventb);
+ if (!result)
+ goto cleanup;
return 0;
cleanup:
marker_remove_probe(probe_subsystem_event);
+ marker_remove_probe(probe_subsystem_eventb);
return -EPERM;
}
static void __exit probe_fini(void)
{
marker_remove_probe(probe_subsystem_event);
+ marker_remove_probe(probe_subsystem_eventb);
}
module_init(probe_init);
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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